Implementation of fast lookup table to search class_def by descriptor
Lookup table is a hash table which built at compile time and stored
into oat file. At runtime the table is restored and used in the
method DexFile::FindClassDef(const char*) to perform fast search of
the class_def_idx by class descriptor. Advantages of the lookup table
over the HashSet (runtime/base/hash_set.h) are:
1. Lookup table is built at compile time and uses read-only memory at
runtime
2. Lookup table uses less memory then DexFile::Index (less by 80% for
/system/framework/framework.jar on Nexus5)
3. Lookup table does less string comparisons compared with HashSet
(less by 70% for zygote process on Nexus5)
The disadvantage of the lookup table is it increased boot.oat size by
0.2% on Nexus5 and application .oat file by 0.3% in average on Nexus5.
mathieuc changes:
Create lookup table in dex2oat to speed up compilation. Clean up code
to follow style guide and use less static functions. Added
performance measurements.
Compile ~100 APKs 5 times with filter interpret-only:
Before:
real 1m8.989s
user 0m59.318s
sys 0m7.773s
After:
real 1m1.493s
user 0m52.055s
sys 0m7.581s
App launch (AOSP N5 maps, average of 45 runs):
Before: 966.84ms
After: 923.733ms
Launch speedup is 4.7%
Memory usage compared to HashSet index on 50 various APK:
32 bit: HashSet ~625694b vs TypeLookupTable ~404268b
64 bit: HashSet ~1251390b vs TypeLookupTable ~404268b
Bug: 10921004
Bug: 20269715
Change-Id: I7246c1d9ad9fe81fe5c5907a4bf70396d8f9242a
diff --git a/compiler/oat_writer.h b/compiler/oat_writer.h
index d6cb65b..f2fe048 100644
--- a/compiler/oat_writer.h
+++ b/compiler/oat_writer.h
@@ -24,8 +24,8 @@
#include "linker/relative_patcher.h" // For linker::RelativePatcherTargetProvider.
#include "mem_map.h"
#include "method_reference.h"
-#include "oat.h"
#include "mirror/class.h"
+#include "oat.h"
#include "safe_map.h"
namespace art {
@@ -36,6 +36,7 @@
class ImageWriter;
class OutputStream;
class TimingLogger;
+class TypeLookupTable;
// OatHeader variable length with count of D OatDexFiles
//
@@ -49,6 +50,11 @@
// ...
// Dex[D]
//
+// TypeLookupTable[0] one descriptor to class def index hash table for each OatDexFile.
+// TypeLookupTable[1]
+// ...
+// TypeLookupTable[D]
+//
// OatClass[0] one variable sized OatClass for each of C DexFile::ClassDefs
// OatClass[1] contains OatClass entries with class status, offsets to code, etc.
// ...
@@ -168,6 +174,7 @@
size_t InitOatHeader();
size_t InitOatDexFiles(size_t offset);
+ size_t InitLookupTables(size_t offset);
size_t InitDexFiles(size_t offset);
size_t InitOatClasses(size_t offset);
size_t InitOatMaps(size_t offset);
@@ -177,6 +184,7 @@
SHARED_REQUIRES(Locks::mutator_lock_);
bool WriteTables(OutputStream* out, const size_t file_offset);
+ bool WriteLookupTables(OutputStream* out, const size_t file_offset);
size_t WriteMaps(OutputStream* out, const size_t file_offset, size_t relative_offset);
size_t WriteCode(OutputStream* out, const size_t file_offset, size_t relative_offset);
size_t WriteCodeDexFiles(OutputStream* out, const size_t file_offset, size_t relative_offset);
@@ -199,6 +207,8 @@
const uint8_t* dex_file_location_data_;
uint32_t dex_file_location_checksum_;
uint32_t dex_file_offset_;
+ uint32_t lookup_table_offset_;
+ TypeLookupTable* lookup_table_; // Owned by the dex file.
std::vector<uint32_t> methods_offsets_;
private:
@@ -333,6 +343,9 @@
uint32_t size_oat_class_status_;
uint32_t size_oat_class_method_bitmaps_;
uint32_t size_oat_class_method_offsets_;
+ uint32_t size_oat_lookup_table_alignment_;
+ uint32_t size_oat_lookup_table_offset_;
+ uint32_t size_oat_lookup_table_;
std::unique_ptr<linker::RelativePatcher> relative_patcher_;